Abstract: Proton magnetic resonance (pmr) has proved to be a useful technique for following the behavior of water in the complex equilibria produced when water is added to solutions of di-(2-ethylhexyl)sodium sulfosuccinate, (Aerosol OT), in n-octane. This system passes through several clear and turbid phase transitions as water content is increased. On the basis of the appearance and location of water proton peaks in the various phases as compared to bulk water, it was possible to differentiate between solubilized and separated water and to draw some conclusions as to the participation of water in these phase transitions.